It is common that novel online media services for e.g. music and movies use peer-to-peer (P2P) techniques for media distribution between the users, also referred to as peers. FIG. 1 illustrates schematically P2P sharing of content such as e.g. media content between a number of peers 103, 104, 109. In FIG. 1 it is illustrated that a media server 101 distributes content related to e.g. a music service 102 or a movie service 115. The peers 103, 104, 109 are able to download content from the media server 101 via an IP network 108, such as the Internet, as is schematically illustrated by arrows 105, 106 and 113. A key characteristic is that users that download content will also at the same time upload (share) the downloaded content to the other users that are interested in the same content. This is shown in FIG. 1 with dashed arrows 107 and 114 indicating that the peers 103 and 109 are also uploading content to the peer 104. By doing this, the service will scale with the number of peers without the need for additional hardware, like streaming servers. Additionally, this will improve the download speed for all users—the more users that are using the service, the better it will perform.
With the success of mobile broadband, the novel online media services enter also the wireless communication networks, alternatively referred to as mobile networks. This means that mobile users in a radio access network (RAN) also assist in P2P content distribution. In FIG. 1 a wireless communication network 110 is illustrated. The peer 109 is a wireless user equipment (UE) that participates in P2P sharing via a RAN 111 and a core network (CN) 112.
In wireless communication networks, the uplink, i.e. the direction from the mobile users to the network, has limited capacity and the UE has limited output power and battery capacity. A majority of the users are indoors and suffer from high building penetration losses. Accordingly bandwidth limitations in the uplink cause particular problems that need to be addressed.
For handheld smartphones the support of the media services is today solved by creating specific media service applications (so-called apps) that do not utilize the P2P techniques, i.e. no sharing, to avoid the uplink transmissions and only receive media content in the downlink (i.e. in the direction from the network to the mobile users). Media applications on laptops and PCs with wireless data cards or dongles for Internet access will on the other hand act as traditional P2P media applications for fixed access. Hence, these types of devices will generate a large load in the uplink due to media seeding and the battery consumption can be negatively affected for mobile devices without AC power. The main cause is that these devices participate in the media distribution more or less all the time when these devices are switched on and the media application is running. The media distribution can not be turned off since the services are designed to exploit this.
Caching in wireless communication networks is a relatively known technology. Caching is based on that a large percentage of Internet traffic is repetitive and that eliminating repeating content all the way from its origin may offer an opportunity to reduce traffic and increase download speed. Therefore, the main principle is that copies of the content in e.g. the Internet are moved closer to the mobile users and stored in a cache, for example in different parts of the RAN, in the CN or just “above” the CN.
The main benefits that can be achieved with caching in wireless communication networks are:                Decrease the cost of transport in the wireless communication network. This is achieved “above the cache” as the cached information in principle is only transferred once in the transmission links above the cache.        Improved Quality of Experience for the mobile end-users. This is mainly achieved with lower delays as the cached information can be returned faster to the mobile users from the cache compared to if the information would be retrieved all the way from the original location.        Provide new services such as content hosting and storage/backup for operators. Mobile operators can sign agreements with the content providers that are based on that the mobile operator ensures that the content from a specific content provider is delivered in a better way to the mobile users in the mobile operator's network.        
Caching can also be used for the content distribution towards the mobile users as illustrated in FIG. 2. Instead of retrieving the downloadable content from the media server 101, the content can be retrieved from a cache 21 located in the wireless communication network 110. Arrow 24 illustrates that content from the media, server 101 is pushed in to the cache 21 in the wireless communication network 110 and then the wireless UEs 109 will receive the content directly from the cache 21, illustrated by dashed arrows 22 and 23, instead of from the media server 101. It is also worth mentioning that caching can be used for almost any Internet content and that FIG. 2 is just an example based on media services.
As mentioned above examples of problems with the prior art solutions for delivery of P2P media services in mobile networks are:                Additional pressure and load on the already limited wireless uplink.        Negative impact on the battery lifetime of the mobile UEs.        The need to handle different application versions for the handheld smartphones and the laptops/PCs.        